One of them traced it back to the Prophet ﷺ, who said, "Jibreel used to stuff mud into Pharaoh's mouth, fearing that he might say, 'There is no god but Allah.'"
حدثنا محمد بن جعفر حدثنا شعبة عن عدي بن ثابت وعطاء بن السائب عن سعيد بن جبير
رفعه أحدهما إلى النبي ﷺ قال إن جبريل كان يدس في فم فرعون الطين مخافة أن يقول لا إله إلا الله
Its isnad is sahih. Tayalisi related it (2618) with a similar meaning from Shubah, as a raised hadith, and it will come again later with this same isnad (3154). Ibn Kathir cited it in his tafsir (4:330) from Tayalisi and said, "Abu Isa Tirmidhi also related it, and Ibn Jareer also related it through more than one route from Shubah," and he mentioned something similar, and Tirmidhi said, "hasan gharib sahih."In one version found in Ibn Jareer, transmitted from Muhammad bin Muthanna from Ghundar from Shubah from Ataa and Adi from Saeed from Ibn Abbas, one of the two narrators raised it while the other apparently did not raise it. This is a reference to this very isnad, for Muhammad bin Jafar is indeed Ghundar.